# -*- coding: utf-8 -*-


# 判断入参是否为空，为空返回字符串
def isNull(str):
    if str is not None:
        return str.strip()
    return ''


# 去除不可见字符
def confir(str):
    if str is not None:
        return ''.join(e for e in str if e.isalnum())
    return ''
